From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 7 Nov 2024 00:16:25 +0000 (-0800)
Subject: maint: expand heap a bit less aggressively
X-Git-Tag: v9.6~114
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5af1b2662b03f42abac46517a7922593eda448b5;p=thirdparty%2Fcoreutils.git

maint: expand heap a bit less aggressively

* gl/lib/heap.c (struct heap, heap_alloc, heap_insert)
(heapify_down, heapify_up): Prefer idx_t to size_t for sizes.
(heap_insert): Use xpalloc instead of x2nrealloc.
(heapify_down): Return void since no caller cares about value.
* gl/modules/heap: Depend on idx.
---

diff --git a/gl/lib/heap.c b/gl/lib/heap.c
index 577997d84d..084731959a 100644
--- a/gl/lib/heap.c
+++ b/gl/lib/heap.c
@@ -25,23 +25,23 @@
 #include "xalloc.h"
 
 static int heap_default_compare (void const *, void const *);
-static size_t heapify_down (void **, size_t, size_t,
-                            int (*) (void const *, void const *));
-static void heapify_up (void **, size_t,
+static void heapify_down (void **, idx_t, idx_t,
+                          int (*) (void const *, void const *));
+static void heapify_up (void **, idx_t,
                         int (*) (void const *, void const *));
 
 struct heap
 {
   void **array;     /* array[0] is not used */
-  size_t capacity;  /* Array size */
-  size_t count;     /* Used as index to last element. Also is num of items. */
+  idx_t capacity;   /* Array size */
+  idx_t count;      /* Used as index to last element. Also is num of items. */
   int (*compare) (void const *, void const *);
 };
 
 /* Allocate memory for the heap. */
 
 struct heap *
-heap_alloc (int (*compare) (void const *, void const *), size_t n_reserve)
+heap_alloc (int (*compare) (void const *, void const *), idx_t n_reserve)
 {
   struct heap *heap = xmalloc (sizeof *heap);
 
@@ -79,8 +79,8 @@ int
 heap_insert (struct heap *heap, void *item)
 {
   if (heap->capacity - 1 <= heap->count)
-    heap->array = x2nrealloc (heap->array, &heap->capacity,
-                              sizeof *(heap->array));
+    heap->array = xpalloc (heap->array, &heap->capacity, 1, -1,
+                           sizeof heap->array[0]);
 
   heap->array[++heap->count] = item;
   heapify_up (heap->array, heap->count, heap->compare);
@@ -107,16 +107,16 @@ heap_remove_top (struct heap *heap)
 
 /* Move element down into appropriate position in heap. */
 
-static size_t
-heapify_down (void **array, size_t count, size_t initial,
+static void
+heapify_down (void **array, idx_t count, idx_t initial,
               int (*compare) (void const *, void const *))
 {
   void *element = array[initial];
 
-  size_t parent = initial;
-  while (parent <= count / 2)
+  idx_t parent = initial;
+  while (parent <= count >> 1)
     {
-      size_t child = 2 * parent;
+      idx_t child = 2 * parent;
 
       if (child < count && compare (array[child], array[child + 1]) < 0)
         child++;
@@ -129,22 +129,21 @@ heapify_down (void **array, size_t count, size_t initial,
     }
 
   array[parent] = element;
-  return parent;
 }
 
 /* Move element up into appropriate position in heap. */
 
 static void
-heapify_up (void **array, size_t count,
+heapify_up (void **array, idx_t count,
             int (*compare) (void const *, void const *))
 {
-  size_t k = count;
+  idx_t k = count;
   void *new_element = array[k];
 
-  while (k != 1 && compare (array[k / 2], new_element) <= 0)
+  while (k != 1 && compare (array[k >> 1], new_element) <= 0)
     {
-      array[k] = array[k / 2];
-      k /= 2;
+      array[k] = array[k >> 1];
+      k >>= 1;
     }
 
   array[k] = new_element;
diff --git a/gl/lib/heap.h b/gl/lib/heap.h
index e000621980..badfe645a0 100644
--- a/gl/lib/heap.h
+++ b/gl/lib/heap.h
@@ -18,13 +18,15 @@
 /* Full implementation: GDSL (http://gna.org/projects/gdsl/) by Nicolas
    Darnis <ndarnis@free.fr>. Adapted by Gene Auyeung. */
 
+#include "idx.h"
+
 #include <stddef.h>
 
 struct heap;
 
 void heap_free (struct heap *) _GL_ATTRIBUTE_NONNULL ();
 
-struct heap *heap_alloc (int (*) (void const *, void const *), size_t)
+struct heap *heap_alloc (int (*) (void const *, void const *), idx_t)
   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC (heap_free, 1)
   _GL_ATTRIBUTE_RETURNS_NONNULL;
 
diff --git a/gl/modules/heap b/gl/modules/heap
index 97e9df2d4b..7140842981 100644
--- a/gl/modules/heap
+++ b/gl/modules/heap
@@ -6,6 +6,7 @@ lib/heap.c
 lib/heap.h
 
 Depends-on:
+idx
 stdlib-safer
 xalloc